Storage battery is an essential part of a vehicle. It provides not only a powerful starting current (generally up to 200 A˜600 A) for the engine, but also an operating voltage for the instruments or other devices within the vehicle (for example, when the engine is idling or stops). Typically, during the operation of the engine, when the voltage of the generator is higher than the voltage of the storage battery, the storage battery will convert part of the electrical energy into chemical energy for storage (so called charging) so that the battery always maintains sufficient power.
But sometimes, the battery may be over-discharged and become insufficient in power because of the negligence of the driver. For example, when the driver leaves the vehicle without turning off the lights or other electrical equipment, or if a vehicle is left unused for a long time, the battery will die. As another example, the battery performance may significantly drop after long-time use because of consumption of the chemicals inside of battery.
However, no matter what is the cause of insufficient battery power, the driver has to endure great inconveniences, e.g., the engine of the vehicle cannot be started. Once this happens, it is common to borrow power from another vehicle (referred as a “rescuing vehicle” hereinafter) and connect 1 battery of said rescuing vehicle to the insufficient power battery via a set of wires for emergent charging.
In prior art, the set of wire typically includes two separate wires and each end of the wires is provided with a clip. In order to establish a circuit between the two batteries, it is required to connect each pole of one battery with the corresponding pole having the same polarity of the rescuing vehicle's battery (that is, positive to positive; negative to negative). However, there is a high risk in the process that, if the battery polarity is mistaken, the two batteries would be in a reverse connection state which is apt to produce sparks and even cause explosion and other damages or injuries. Furthermore, if the operating voltages of the two batteries do not match, the vehicle may incur damages and other risks.